Packaged microelectronic devices, such as memory chips and microprocessor chips, typically include a microelectronic die mounted to a substrate and encased in a plastic protective covering. The die includes functional features, such as memory cells, processor circuits, and interconnecting circuitry. The die also typically includes an array of very small bond-pads electrically coupled to the integrated circuitry. The bond pads are coupled to pins or other types of terminals that extend outside the protective covering for connecting the microelectronic device to buses, circuits and/or or other microelectronic assemblies. The individual dies are typically “packaged” to couple the bond-pads to a larger array of electrical terminals that can be more easily coupled to various external devices.
An individual die can be packaged by electrically coupling the bond-pads on the die to arrays of pins, ball-pads, or other types of electrical terminals, and then encapsulating the die to protect it from environmental factors such as moisture, particulates, static electricity, and physical impact. For example, in one conventional arrangement a packaged device includes an interposer substrate having a front side and a backside. The interposer substrate also includes a plurality of conductive structures on and/or in the substrate. More specifically, a typical interposer substrate includes a plurality of conductive “bumps” or pads at the front side, a plurality of ball-pads at the backside, and a plurality of vias or traces electrically coupling the conductive pads to corresponding ball-pads. A die can be positioned at the front side and attached to the interposer substrate. In one application, for example, a die is “flipped” such that an active side of the die with the bond-pads faces downward for attachment to the front side of the substrate. The bond-pads are usually coupled to the corresponding conductive pads such that the die is electrically and mechanically coupled to the substrate.
A significant limiting factor for manufacturing packaged microelectronic devices is forming the conductive structures on and/or in the interposer substrate to which the bond-pads on the die are attached. One approach has been to fabricate interposer substrates with a number of conductive pads corresponding to the specific line count for a particular type of die. More specifically, individual interposer substrates can be manufactured having specific conductive line configurations (e.g., ×4, ×8, ×16, ×32, etc.) for use with particular die configurations. One drawback with this approach, however, is that it is very expensive to manufacture interposer substrates having a single configuration for a specific type of die. The manufacturing process requires tailoring an individual reticle (e.g., a mask) for each separate device configuration. For example, a mask used to fabricate a device with a ×4 line configuration can not be used to fabricate a device with a ×16 line configuration. Accordingly, the mask must be installed on a dedicated machine for fabrication of the interposing devices having that particular line configuration. As such, if several different line configurations are required (e.g., ×4, ×8, ×16) for a particular run of dies, then three separate fabrication processes and/or machines are required to manufacture the various interposing devices. Accordingly, conventional processes for constructing interposer substrates are relatively expensive.